I understand the 380 model has three different engines fitted to it depending on where you live.
116. 961
116. 962
116. 963
Are they all the same or differ in something?
Which idle speed actuator(valve) is the correct one for engine
116. 961.
Should I use 000 141 12 25 or
000 141 13 25 or
000 141 14 25
Thank you all if anyone can help this.

Here's what I could find out. The 116.963 was in the 380SE, 380SEL and 380SEC. The 116.962 was in the 83-85 380SL and the 116.960 was in the 81-82 380SL. I couldn't find a reference to the 116.961. I am not sure if all European models are numbered the same as these, if your car was originally delivered to North America I am pretty sure you have the 116.963. Based on the numbers I am assuming the 116.960 was for the 380SL with single rail timing chain, and the 116.962 was with the double rail. It is possible the 116.963 was for the 380 Sedan with double row timing chain and the 116.961 (which I couldn't find a refence for, but which you mentioned you thought you had) could have been for the 380 Sedans with a single row timing chain.

As for which idle speed actuator you need, I couldn't find any info on that. The partsshop here lists all three as unavailable or out of stock.

As it turns out all US models 116.960/961/962/963 use the idle valve 000 141 12 25.

The 116.961 is a 1981 380SEL at least in the US models.

116.961 engine
 

If my memory serves me right (had 82 380 SE, got broadsided and totaled) the 116.961 was European , double row chain, high compression version, and ran like a scalded cat! Euro version did not have electronic idle speed control.